Transcutaneous spinal direct current stimulation inhibits nociceptive spinal pathway conduction and increases pain tolerance in humans

Abstract

Despite concerted efforts from pharmacologic research into neuropathic pain, many patients fail to achieve sufficient pain relief with medication alone. For this reason, increasing interest centres on neurostimulation techniques. We assessed whether transcutaneous spinal direct current stimulation (tsDCS) modulates conduction in ascending nociceptive spinal pathways. We measured changes induced by anodal and cathodal tsDCS over the thoracic spinal cord on face- and foot-laser evoked potentials (LEPs) and foot-cold pressor test responses in 20 healthy subjects. Whereas anodal tsDCS reduced the amplitude of the N1 and N2 components of foot-LEPs (P<0.05) neither anodal nor cathodal tsDCS changed LEPs evoked by face stimulation. Pain tolerance to the cold pressor test was significantly higher after anodal than after cathodal tsDCS (P<0.05). Conversely, no difference was found in the pain threshold or pain ratings to the cold pressor test between the two polarity conditions. Our data suggest that anodal tsDCS over the thoracic spinal cord might impair conduction in the ascending nociceptive spinal pathways, thus modulating LEPs and increasing pain tolerance in healthy subjects.

Abdominal acupuncture reduces laser-evoked potentials in healthy subjects

“…Indeed, we can suppose that the neurophysiological assessment of the nociceptive pathway is more sensitive to slight pain modifications than the subjective psychophysical rating. This was also found when more standardized analgesic treatments, such as the transcutaneous spinal direct current stimulation, were tested (Truini et al, 2011).…”

Does Trans-Spinal Direct Current Stimulation Alter Phrenic Motoneurons and Respiratory Neuromechanical Outputs in Humans? A Double-Blind, Sham-Controlled, Randomized, Crossover Study

“…tsDCS may have interfered with cortical excitability, as tsDCS applied to the thoracic level modulated the cervicomedullary P30 component of the posterior tibial nerve somatosensory-evoked potential (Cogiamanian et al, 2008) and attenuated the spinal processing of nociceptive inputs (Truini et al, 2011), suggesting that tsDCS influences conduction along ascending (lemniscal/ spinothalamic) tracts. To test this hypothesis, we measured sICI, a common method used to investigate changes in GABA A intracortical synapses in the motor cortex , in the diaphragm (Demoule et al, 2003b;Sharshar et al, 2004).…”

“…Polarity of stimulation refers to the spinal electrode. The stimulus intensity was set at 2.5 mA and was applied over a 15 min period (Cogiamanian et al, 2008;Winkler et al, 2010;Lamy et al, 2012) resulting in a current density of 0.071 mA/cm 2 and a delivered total charge of 64 mC/ cm 2 . The current was ramped up to 2.5 mA over a 10 s period and similarly ramped down at the end of stimulation.…”

“…Recently, there has been a growing interest in application of DC stimulation over the spinal cord [transcutaneous spinal direct current stimulation (tsDCS)] because of its acceptable safety record, low cost, and potential use in outpatients . Indeed, in humans, it has been shown that tsDCS can modulate activity in lemniscal (Cogiamanian et al, 2008), extralemniscal (Cogiamanian et al, 2011;Truini et al, 2011), and corticospinal (Lim and Shin, 2011) tracts, as well as segmental spinal motor circuits (Winkler et al, 2010;Lamy et al, 2012). Although the mechanisms underlying tsDCS aftereffects are poorly understood at the present time, several studies have suggested that (1) glutamatergic neurotransmission is altered after tsDCS (Ahmed and Wieraszko 2012), leading to the assumption that tsDCS aftereffects are likely to occur via activation of neuronal processes terminating in the spinal cord, which are responsible for expression of long-term potentiation in postsynaptic spinal cord motoneurons; (2) DC polarization could affect the intrinsic properties of the motoneurons (Ahmed, 2011); (3) tsDCS could modulate the spontaneous discharges in ventral roots (Fuortes, 1954;Ahmed, 2011); and (4) tsDCS aftereffects differ according to the direction of the current and the position of the electrodes (Ahmed, 2014;Parazzini et al, 2014).…”

Alternative Therapiemethoden bei RLS

“…Bei der tsDCS erfolgt die Applikation eines leichten Gleichstroms transkutan über dem thorakalen Rü-ckenmark. Eine anodale tsDCS zeigte in mehreren Studien inhibitorische E ekte auf die spinale Exzitabilität und resultierte in einer erhöhten Schmerztoleranz [25,26,27,28].…”